Non-petroleum-based energy generation is an area of high technical and political interest. Systems that produce energy without the combustion of petroleum products potentially offer alternatives to conventional energy generation plants that are renewable, cleaner, potentially cheaper, and potentially more reliable.
Ocean thermal energy conversion (OTEC) is one such promising energy technology. An OTEC system converts solar radiation to electrical energy by using a naturally occurring temperature difference between water at the surface of a large body of water and water thousands of meters deep to drive a power-producing cycle. As long as the temperature between the warm surface water and the cold deep water differs by about 20° C., an OTEC system can produce a significant amount of power. Large bodies of water, such as oceans, therefore, represent vast renewable energy resources, which can be relatively easy to access.
A typical conventional OTEC system uses an electrical generation system, which is located at the surface and produces electrical energy using the temperature differential between two heat exchangers. A first heat exchanger uses the heat from warm surface water to vaporize a fluid contained in a closed-loop conduit. The energy of the vaporized fluid is used to turn a turbine, which turns an electrical generator that generates electrical energy. After the vaporized fluid passes through the turbine, it is channeled by the conduit to the second heat exchanger. The second heat exchanger uses cold water piped up from the depths of the body of water to condense the vapor back into the liquid state. The cold water received by the second heat exchanger is typically pumped up to it from a depth of 1000-2000 meters. The water is pumped to the heat exchanger through a cold water pipe that extends from the surface of the ocean to the deep water level. Another pump then pumps the working fluid back to the first heat exchanger where the cycle begins again.
Although a promising technology, to date, the use of OTEC power generation has been limited by a number of technical challenges. First, the significant amount of energy required to run an OTEC plant reduces its overall benefits. Second, conventional OTEC plants are highly susceptible to damaging winds, waves, and hurricanes and other storms. Finally, an OTEC plant requires complex and expensive infrastructure to enable its deployment.